As you see, currently it's not worth it buying these keys as they are 500 Timeless Coins each unless you're farming for the pet - as the average payout for one coins seems to be 100-150 coins lower than the cost of the key. Also it's highly likely that the maximum number of coins a chest can contain is higher than 950, I just wasn't lucky enough.

Note: I also spent ~33k coins around the time of the hotfix and got no burdens but 2x bonkers at that time. If it was post nerf then that would raise my average coin investment per burden up to 45k coins. It is still very unclear whether it is worth gambling for burdens or not, but as long as it stays under 50k investment per burden then it is worth it to get all the extra gear tokens and bonkers if you don't have 3x already if you don't mind gambling.

Old Information:With the PTR ending I found myself with tons of coins and not much to do with them so I decided to research Kukuru's Cache Key sold by Master Kukuru for 500 Timeless Coin which open various Timeless Chests around him.

Starting with 163500 coins and reinvesting any coins looted from the chests into more keys I found out the follow:

Chests usually give 50-1000 coins but has rare chance of 1 coin (~1%) and even rarer chance of 10,000 coins (0.1%?). They always have only one thing in them, either one piece of loot or coins.72.66% avg coin refund if you were to get no other type of loot63.96% avg coin refund factoring in other loot

Comment by Eliva2009

It gets too tempting after buying a bunch of these keys to keep going "One more... just ooooone mooooore"

Comment by taii93

As of 9/12/2013, it's possible to get up to 10,000 coins from a chest. I've opened around 100 so far between all of my alts, but only gotten above 1,000 coins once, and it was the 10k.

Comment by dudley

Ok, I'll share my results as well. Like already said it's a really good opportunity on spending Coins if you aim for the Burden of EternitySummed up I got 13 tokens, the pet and one burden for 15k Coins by spending them all including the refunds.

Comment by KarmaKingRatt

A BOAT'S A BOAT, but the mystery box could be anything. IT COULD EVEN BE A BOAT. You know how much we wanted one of those...

Comment by selahbela

I bought around 18 keys and got 1 Burden of Eternity, and 13 armor/curio tokens. I feel really lucky!

Maybe I'm just really easily entertained, but this grotto has given me the most fun out of WoW I've had in a long time. lol

Comment by ginie66

This has been nurfered and is now a coin sink.

YesterdayStarted with 24keys - 8 epics 1 Burden of Eternitywas able to get 11 more - 3 epics and no Burden of Eternitywas able to get 7 more - 2 epics and 1 Burden of Eternitywas able to get 2 more - 1 epics and no Burden of Eternity

Today

Started with 56 keys- 6 epics no Burden of Eternitywas able to get 36 more - 5 epics and no Burden of Eternitywas able to get 18 more - 3 epics and no Burden of Eternitywas able to get 11 more - 2 epics and no Burden of Eternitywas able to get 7 more - 1 epic and no Burden of Eternitywas able to get 6 more - 0 epic and no Burden of Eternitywas able to get 3 more - 0 epic and no Burden of Eternity was able to get 1 more - 0 epic and no Burden of Eternity

All in all this was a waist of coins and time today

Hope you have better luck

Comment by Tandoras

Thought I should share my results with you all.Decided to buy a couple of Kukuru's Cache Key, the 14th September.

Okay, so to sum it up.If you are a Timeless Coin freak like I know some of you are (*cough*super awesome mount, hello?), then this is not the way to go.However, if you don't care about trivial things like mounts and being awesome - like myself. This would be an awesome way to get gear for your alts, or possibly one of those beautiful Burden of Eternity to lighten up your day and get some very sweet gear in the process!

I did not have high hopes about this, but I have to say that Bonkers made my day!Was it all worth it?Yes! The Timeless Coin can be easily farmed, and the chance to pets and Burden of Eternity makes this worth it any day of the week! Perhaps it will take you longer to get that charming Reins of the Heavenly Golden Cloud Serpent, but on the other hand.. There is always the chance for the 10,000 Timeless Coin drop from using a Kukuru's Cache Key ;)

Comment by Dontlookdown

I used 200 keys between patch day Teusday and Wednesday. I got ZERO Burdens of Mortality, 4 bonkers! I wasn't happy about that. Everyone's luck is different I guess.

Comment by Barringa

I've seen all sorts of superstitious behaviour around these chests. Like one guy standing in front of the biggest, golden treasure chest, waiting for it to respawn so he could loot it again. I myself was thinking it might be a Last Crusade sort of situation, where the plainest and smallest thing is actually the best. Who knows if there's a certain chest that has a better reward, but I highly doubt it. I've gotten 2 Burdens from Kukuru, both from completely different looking chests.

Comment by Bluesius

Realistically speaking I just paid 11 700 coins for 13 BoA epics and 2 pets. Judging from other comments it does not seem like I am an edge case, this treasure chest is essentially a way to dump coins for BoA gear, in terms of pure coin per coin gain, the house wins (we expected this), but its a neat way to stock up on gear.

Comment by Smixor

Wanted to share my results as well :)

I bought 100 Keys (50,000 Timeless Coins). In total I ended up with; 13 Gear tokens1 Bonkers1 Burden of Eternity& I made 30,100~ coins back in total.

Happy 'chest-openings' everyone.

____________________________Edit: In addition I bought 109 extra keys and got 14 Gear tokens + 2 Bonkers, was rather sad, not to see another Burden

Comment by Dr00dboy

Used about 300 keys13 pieces of timeless gear6 bonkers

Comment by Sivvo97

Okay, so to make some of you feel bad, and make myself feel even better I just purchased 8 keys and found one burden of eternity, one bonkers and ended up earning 3350 timeless coins back. My best luck ever!

I was hoping for more than one Burden of Eternity as I had earlier experiences where I'd get around 2 from 30k coins. :(

Comment by Mystico21

Yesterday (May 14th), after looking at my currency screen and seeing that I have 35k coins I thought I should try my luck with this guy's chests instead of grinding 15k more to buy a Burden of Eternity.

I opened a total of 196 chests and this is what I got:__________________________________________________________26 x Timeless Armor Tokens:-------- 6 of them were Timeless Cloaks. (Am I the only one that thinks the cloak has the highest drop chance out of all the Timeless Armor Tokens?)-------- 1 x Timeless Signet-------- 1 x Timeless Lavalliere-------- The rest were different armor tokens. Only 3 of them were duplicates.2 x Bonkers1 x Burden of Eternity

I got the Burden of Eternity at ~100th chest opened but I kept on going until I had ~300 coins left and couldn't buy keys anymore.

I did a little math and 196 x Kukuru's Cache Key = 98k coins. Knowing I had 35k when I started means that I looted 63k coins from the 196 chests. That's an average of ~321 coins per chest. The most coins I got from a single chest was 900 (only once) and the least I got was 1 (yes, only 1 (ONE) coin from a chest, and not once but three times).